This invention relates to a navigation and communication system for underwater divers.
Underwater visibility is usually very poor, with range in coastal regions typically limited to between five and fifteen feet. In deep water, darkness and absence of color further reduce the visibility of landmarks. In order to navigate underwater, the diver conventionally has been required to figure his course in terms of distance and heading prior to entering the water. With some idea of how fast he is able to swim, the diver typically travels for a period of time corresponding to the desired distance, measured with a wristwatch, at the determined heading, measured with a hand-held compass. In many cases, the diver's underwater course is indirect, and includes several legs, i.e., distances travelled at different headings. These legs must all be determined prior to the dive.
Presently, the United States Navy uses the Swimmer Area Navigation System, which allows a diver to determine and record his current position in relation to diver-planted markers as position references. Each marker is equipped with an acoustic transducer, and a clock for keeping precise real time. Periodically at predetermined times, each marker transducer emits a ping, and the diver has a unit which determines his position relative to the markers, based on the predetermined time of sending the respective pings and the measured time of reception of the pings at the diver unit. Since these markers are not referenced to anything fixed in the environment, coordinates determined under one setup are unusable under another setup.
It is therefore an object of this invention to provide a diver navigation system enabling a diver to determine his position relative to fixed earth coordinates.
Another object of this invention to provide a diver navigation and communication system, which provides the capability of determining the position of a diver and reporting such position to a base station.
It is a further object of this invention to provide a system which provides two-way communication between a diver and a base station.
A further object is to provide a system which directs the diver to a desired destination.